High-energy nuclear reactions of niobium with incident protons and helium ions

Abstract

High-energy nuclear reactions initiated by protons and He ions on Nb were investigated. Specific reaction products were selected to represent the low and high deposition energy processes as well as the production of low-mass products. Excitation functions for these products were determined at 240 to 720 Mev for incident protons, and 320 to 880 Mev for incident He ions. The results from the proton bombardments were compared with values obtained from a Monte Carlo calculation of the cascade-evaporation model. The results from the proton bombardments were also compared with those from Heion bombardments. In general, the comparison of experimental proton results with the results from the calculation gives satisfactory agreement for the low and high deposition-energy processes with the exception of specific cases such as the (p, pxn) reactions. This agreement might be improved with suitable refinements of the calculation. However, the calculation is not able to predict the production of low-mass products, and therefore another mechanism must be invoked to explain their production. The comparison between the experimentally determined proton and He- ion results shows a remarkable similarity. This similarity was unexpected from a consideration of high-energy processes such as meson production and interaction. The inconsistencies which arise from this observation are presented. In addition, experimental information for the identification and decay properties of the previously unreported Nb/sub 88/ isotope is given.